adding log information to show prograss
change of file open options:os.O_CREATE|os.O_EXCL|os.O_RDWR
add header
rename function name for clarity
added error message if generated file exists
uncomment example router namespace: object & user
Merge pull request #32 from ZhengYang/master

[Bug Fix] Added os.O_EXCL flag to make sure existing files are NOT overwritten